When you build the project, Xcode creates a folder for your project in the derived data folder and places the files it creates in that folder. If you want your derived data in a different location, open Xcode’s Location Preferences. Choosing File > Project Settings lets you change the derived data location for a single project.

Update

You can also open the folder where your application resides using the Xcode project window. Click the disclosure triangle next to the Products folder in the project navigator. Select the application, right-click, and choose Show in Finder.

Is the name of the product in red text in the project navigator? If so, the Show in Finder menu item is going to be disabled because Xcode can’t find the path to the application. I have this problem with one project, and I haven’t been able to fix it yet. If I find a solution, I’ll post it here. If you find a solution before me, please post it here.

I found the above instructions confusing, and perhaps wrong for xCode 5.0.2 under 10.8.5 … “Show in Finder” doesn’t work.

What works is from the ____.xcodeproj window click the triangle to expose the contents of Products, and then click on the content. On the right-hand side of the window the “identity and type” pane will give you the full path.